I just started experiencing some issues on Ubuntu 12.04 with Chrome Version 20.0.1132.47 after a software update.
The problem is specific to this version on Ubuntu.
I tested the same Chrome version on Windows and it is fine.
When replying to posts on forums or opening posts in edit mode, Chrome is not allowing the cursor to enter the edit area and appears to be treating it like an image.
Also seeing some artifacts of previous pages on the right hand border of the page.
This is symptomatic of a problem with the renderer
It's nothing to do with our forum upgrade from 4.1.11 to 4.2.0.
I tested with other browsers and it is all fine.
I tested with the development version Chromium Version 21.0.1143.0 custom (138003) and the problem has gone away again.
That is not the latest verion of Chromium, but is a step or two further on than the version of Chrome that I am having the issue with.
I'm not sure how this bug got into a Ubuntu release version of Chrome but there you have it.
So, if you are using Ubuntu 12.04 and have any issues with Chrome Version 20.0.1132.47 like I described above, roll on to the next version or roll back to the previous version and it should be fine.